Signaling system for telegraph links



Aug. 5, 1952 I R. M. M. OBERMAN SIGNALING SYSTEM FOR TELEGRAPH LINKS Filed July 50, 1947 INVENTOR.

RoELoF MAARTEN MARIE OBERMAH BY Patented Aug. 5, 1952 Roeloi' M. M. .Oberman, The Hague, Netherlands Application July 30, 1941, Serial No. 767,521 In the Netherlands April 24, 1944 Section 1, Public Law 690,August 8, 1946 Patent expires April 24, 1964 The invention refers to signalling in a telegraph system which preferably uses teleprintpurpose of the invention is to efiect special signals on a connection e. g. for closing a connection or for operating a particular device in the connection as for instance a monitoring set or a time indicator under the control of this thirtysecond telegraph signal.

Operating particular signallings in telegraph systems by using slowly releasing relays supervising the position of the polar relay armatures is known. It is impossible however due to the considerable divergence inthe release times of such relays, when using them for particular signalsto prevent the printing of undesired signals.

It has been possible to entirely prevent the printing ofundesired signals by means of special interruptors and other structural features in the teleprinters (El. Communication, v. 17, p. 375).

The purpose of the invention is the provision of a signalling system in which particular signals can be sent while using ordinary teleprinters without undesired signals being printed.

v The system of the invention uses to this efiect a supervisory device on the transmission relay armaturcs which can only operate on telegraph signals all of which have equal signalling elements, e. g. mark.

The key set of the printers should be provided with a key which emits, when operated, the signalling combination consisting in the usual five-unit code of a starting element (mark), five marking. signal elements and a stop element (space). This is therefore a normal signal on which the printers start, but do not print. The system of the invention presents the advantage that the printing of undesired signals is prevented during the transmission of the special signal without requiring any special constructions in the teleprinter.

5 Claims. (01. 178-69) The invention will be described with reference to some figures showing an embodiment which is shown as far as is required for illustrating the invention.

Fig. 1 shows the principle of the signalling circu1 Fig. 2 shows the principle of Fig. 1 with a tube added;

Fig. 3 is the circuit of Fig. 1 with a cold cathode gas tube;

Fig. 4 shows a variation of Fig. 2.

The armature a of a polar receiving relay A is supervised in Fig. 1 by the relay LA. The relay A being commutated by the line altemations connects its tongue alternatively to and telegraph battery. Tongue a receives 32 signals in the manner described, every signal being preceded by a start element and followed by a stop element, the teleprinter reacting to 31 of the 32 signals, but not to the thirty-second. The circuit of the invention reacts to this thirty second signal and by sending it a response may be obtained at the receiver resulting e. g. in the control of any desired function. This armature a is'coupled to the charging circuit of a condenser Cl. The latter is connected through a resistive element such as a resistance WI to the armature a, the other condenser pole being connected to a battery pole. Armature a shortcircuits the condenser circuit in spacing position so that it is discharged. I

Energising the polar relay A by telegraph signals causes the armature a to change-over in a certain rhythm to the other battery pole. Condenser Cl is thus charged and discharged in the same'rhythm, the time taken by the charging and discharging of the condenser Cl being dependent on the resistance value of the resistive element WI. The blocking cell or diode SI is connected across the resistance WI, in such a way that it is not conducting while armature a is in contact with the front contact and is conducting while armature a is in spacing position. In conducting condition cell SI has such a low resistance that the condenser Cl is completely discharged when armature a is in spacing position for the time of one signal element, 1. e. during 20 milliseconds for normal five unit code with a speed of 50 Baud. In this manner the discharged condition of condenser Cl at the co'mafter its transmission; a print would be effected? for any other signal in those systems using a lengthy line interruption for signalling pur-- poses.

While armature a is in contact with the marking contact condenser Cl ofFig. 1 receives continuous charging current, i'. e. as long as marking current is transmitted. Cell S2 connected to the junction of condenser Cl and charging resistance WI becomes conducting when condenser Cl is charged to half battery voltage. Relay LA then operates, actuating the signalling system.

The charging time of condenser CI, e. g. the

time that passes between the attraction of armature a and the becoming conductive of cell S2, should be regulated for signals in usual five unit code and a speed of 50 Bauds to 100 milliseconds. Then the signal having the greatest similarity to the special signal cannot operate relay LA. In this manner LA operates during the last 20 milliseconds marking current of the special signal.

: The circuit of Fig. 1 has the disadvantage that, when using a neutral relay, for relay LA, a condenser CI of considerable size is required. This drawback is overcome by the circuit of Fig. 2 using a vacuum or a gas discharge tube BI. The grid of this tube is connected through a protecting resistance W2 to the junction of charging resistance WI and condenser CI. The cathode of tube BI is connected to ground or to a potentiometer. In spacing position of armature a the grid of this tube thus has a high negative voltage with regard to the cathode.

It is remarked that according to the C. C. I. T. (Comit Consultative Internationale sur la Tlgraphique) the armature of a polar telegraph relay should be connected to battery pole in spacing position. The opposite is the case if tubes are used as in the circuit of Fig. 2. With the aid of an auxiliary relay the circuit of Fig. 2 may be made to agree to existing systems.

The charge on condenser Cl is limited to half battery voltage in the circuit of Fig. 2 by providing cell S2. Tube Bl which'preferably only becomes conducting when the grid voltage is slightly negative cannot get positive grid voltages because of the provision of cell S2. This cell, however, may be omitted.

Signalling relay LA attracts when tube Bl becomes conductive, whereby the special signal can now be received.

The anode voltage of tube Bl may be derived from the positive half of telegraph battery.

Fig. 3 shows the signalling circuit when a cold cathode gas filled tube is used. The anode of this tube B2 is connected through signalling relay LA to the positive pole of telegraph battery. The cathode is connected to the negative pole of the telegraph battery. The grid of this tube is connected through protecting resistance W2 to the junction of resistance Wi and condenser 4 Cl. Condenser Cl should be charged so far after about 110 milliseconds that tube B2 ignites. Signalling relay LA operates on ignition of tube 282.

In Fig. 1 the time which the signalling relay LA takes to operate is to a high degree independent of the value of battery voltage as long as both battery halves vary in the same manner. The circuits of Figs. 2 and 3 are, however, not independent of voltage fluctuations of tubes if these tubes have a grid swing which is not small compared to battery voltage.

f It is remarked that if the signalling device is connected tothe armature to be supervised with the application of an auxiliary relay cell SI is not required and may be replaced by resistance ,Wl of Fig. 4. The cathode of tube BI is connected to a top of a potentiometer W4, W5 whereby a certain degree of independence of voltage fluctuations of both battery halves is obtained.

While I have illustrated and described what I regard to be the preferred embodiment of my invention, nevertheless it will be understood that this is merely shown by way of example and that numerous modifications and rearrangements may be made therein without departing from the essence of the invention.

I claim:

1. A telegraph receiving system comprising a local source of D. C.; a receiving line relay; an armature controlled by said' relay so as to alternate between opposite polarities of said D. C. source; a, condenser having one terminal connected to one pole of said D. C. source; a resistance having terminals connected, respectively, to said armature and to the otherterminal of said condenser; a rectifier connected across said resistance between said armature and the other terminal of said condenser so as to become conductive on said armature making contact with said terminal of said D. C. source connected to said condenser; and signalling means being responsive to the voltage of said condenser surpassing a predetermined limit.

2. A telegraph receiving system comprisinga local source of D. C.; a receiving line relay; an armature controlled by said relay so as to alternate between opposite polarities of said D. C. source; a condenser having one terminal connected to one pole of said D. C. source; a resistance having terminals connected, respectively, to said armature and to the other terminal of said condenser; a rectifier connected across said resistance between said armature and the other terminal of said condenser so as to become conductive on said armature making contact with said terminal of said D. C. source connected to said condenser; and signalling means being responsive to the voltage of said condenser surpassing a predetermined limit, and including a tube having a cathode, a grid, and an anode, a resistance connecting said grid with that terminal of said condenser which is connected to said armature, and a signalling line connected to said anode.

3. A telegraph receiving system comprising a local source of D. C.; a receiving line relay; an armature controlled by said relay so as to alternate between opposite polarities of said D. C. source; a condenser having one terminal connected to one pole or said D. C. source; a resistance having terminals connected, respectively, to said armature and to the other terminal of said condenser; a rectifier connected across said resistance between said armature and the other terminal of said condenser so as to become conductive on said armature making contact with said terminal of said D. C. source connected to said condenser; and signalling means being responsive to the voltage of said condenser surpassing a predetermined limit, and including a tube having a cathode, a rid, and an anode, a resistance connecting said grid with that terminal of said condenser which is connected to said armature, and a signalling line connected to said anode.

4. A telegraph receiving system as claimed in claim 3 including means for biassing said grid of said tube to the predetermined limit.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,094,733 Byrnes Oct. 5, 193? 2,287,926 Zepler June 30, 1942 

